Answer:
38
Step-by-step explanation:
substitute the value of the variable into an equation, then simplify
Remove the parentheses around the expression 1
I believe the answer for 17 is C. 18 I am not sure how to do. For 19, however, the answer is B. Hope I help, and sorry I can't answer 18.
Assuming that's a 40 minutes a lesson the minutes the tennis teacher teaches in a week is 800 minutes
Let the two numbers be x and y.
According to your question;
x + y = 7
10y + x = 10x + y + 9
By equation 1 ; x = 7-y
Substituting the value of x ;
10y + ( 7 -y) = 10(7-y) + y + 9
9y + 7 = 70 -10y + y + 9
9y + 7 = 70 - 9y + 9
=> 18y = 70 -7 + 9
=> 18y = 72
=> y = 4
Substituting for x ;
x = 7 - y
=> x = 7 -4
=> x = 3
Thus, x = 3 and y = 4;
=> The number is 34.
